Plant seed coating

Abstract

Plant seeds designed for germination without substantial delay are coated with a first layer of a mixture of sugar and a water insoluble polymeric material, and have a particulate coating adhered to the first layer while the first layer is still tacky, the first layer being preferably formed from an aqueous coating composition which is cured by simple removal of water therefrom.

What is claimed is: 
     
       1. In a coated plant seed comprising a seed having a coating thereon comprising of polymeric material in direct contact with the normally exposed seed surface; the improvement comprising employing as such coating an intimate mixture of sugar and water insoluble polymeric material, the sugar being present in said coating in an amount of from 1/8 to 6 parts by weight per part by weight of said polymeric material. 
     
     
       2. A coated seed product in accordance with claim 1 in which the ratio of sugar to water insoluble polymeric material is from 3/8 to 4 parts by weight of sugar per part by weight of polymeric material. 
     
     
       3. A coated seed product in accordance with claim 2 in which the ratio of sugar to water insoluble polymeric material is from 5/8 to 2 parts by weight per part by weight of polymeric material, and in which the polymeric material is a vinyl acetate homopolymer. 
     
     
       4. In a coated plant seed product in accordance with claim 1 comprising a seed having a first coating thereon comprising a polymeric material in direct contact with the normally exposed seed surface and a particulate coating over and adhered to said polymer coating; the improvement comprising employing as the first coating a mixture of sugar and a water insoluble polymeric material, the sugar being present in said coating in an amount of from 1/8 to 6 parts by weight per part by weight of polymeric material. 
     
     
       5. A coated seed product in accordance with claim 4 in which the ratio of sugar to water insoluble polymeric material is from 3/8 to 4 parts by weight of sugar per part by weight of polymeric material. 
     
     
       6. A coated seed product in accordance with claim 5 in which the ratio of sugar to water insoluble polymeric material is from 5/8 to 2 parts by weight of sugar per part by weight of polymeric material. 
     
     
       7. A coated seed product in accordance with claim 6 in which a second coating comprising a mixture of sugar and a water insoluble polymeric in the weight ratio of from 5/8 to 2 parts of sugar per part of polymeric material covers the particulate coating over the first coating of said mixture of sugar and polymeric material, and in which a second coating of particulate material is coated over and adhered to said coating of sugar and polymeric material. 
     
     
       8. A coated seed product in accordance which claim 6 in which the seed is a leguminous plant seed. 
     
     
       9. A coated seed product in accordance with claim 8 in which the particulate material is calcium carbonate. 
     
     
       10. A coated seed product in accordance with claim 9 in which the polymeric material is a vinyl acetate homopolymer. 
     
     
       11. A coated seed product in accordance with claims 4, 6 or 7 in which a final coating consisting essentially of a water insoluble polymeric material is adhered to the otherwise final coating of particulate material in an amount sufficient to partially seal the coated seed without substantially increasing its germination time. 
     
     
       12. A coated seed product in accordance with claim 11 in which the polymeric material underlying the particulate coating or coatings is a vinyl acetate homopolymer and in which the water insoluble polymeric material of the final coating is polyurea. 
     
     
       13. A coated seed product in accordance with claims 4, 6 or 7 in which the polymeric material is a vinyl acetate homopolymer. 
     
     
       14. A coated seed product in accordance with claims 4, 6 or 7 in which the seed is rice seed or a leguminous plant seed. 
     
     
       15. In the process of coating plant seeds comprising distributing a liquid coating composition over the normally exposed surface of the plant seeds, distributing a particulate material over the resulting liquid coated seed surface while said coating composition is still tacky and effecting at least an effective curing of the coating composition; the improvement comprising employing therein as the coating composition a liquid composition comprising sugar, a water insoluble polymeric material and a liquid carrier for the sugar and polymeric material, the sugar being present in said composition in an amount of from 1/8 to 6 parts by weight per part by weight of said polymeric material. 
     
     
       16. The process of claim 15 in which the ratio of sugar to water insoluble polymeric material is from 3/8 to 4 parts by weight of sugar per part by weight of polymeric material. 
     
     
       17. The process of claim 16 in which the ratio of sugar to water insoluble polymeric material is from 5/8 to 2 parts by weight per part by weight of polymeric material. 
     
     
       18. The process of claim 17 in which the liquid carrier is an organic solvent in which the polymeric material is dissolved and in which the sugar is suspended. 
     
     
       19. In the process of coating seeds in accordance with claim 15 comprising distributing a liquid coating composition over the normally exposed surface of the plant seeds, distributing a particulate material over the resulting liquid coated seed surface while said coating composition is still tacky and effecting at least an effective curing of the coating composition; the improvement comprising employing therein as the coating composition an aqueous composition comprising water, a preformed water insoluble polymeric material dispersed in said water and sugar, and effecting the curing of said composition by the simple removal of water from said composition, the sugar being present in said composition in an amount of from 1/8 to 6 parts by weight per part by weight of said polymeric material. 
     
     
       20. The process of claim 19 in which the ratio of sugar to water insoluble polymeric material is from 3/8 to 4 parts by weight per part by weight of polymeric material. 
     
     
       21. The process of claim 20 in which the ratio of sugar to water insoluble polymeric material is from 5/8 to 2 parts by weight per part by weight of polymeric material. 
     
     
       22. The process of claim 21 in which the curing is effected at room temperature. 
     
     
       23. The process of claim 22 in which the sugar is dissolved in the water of the coating composition. 
     
     
       24. The process of claim 23 in which the coating composition is essentially free of organic solvents. 
     
     
       25. The process of claims 21 or 24 in which the seed is a leguminous plant seed. 
     
     
       26. The process of claim 25 in which the particulate material is calcium carbonate. 
     
     
       27. The process of claim 26 in which the polymeric material is a vinyl acetate homopolymer. 
     
     
       28. The process of claim 20 in which the seeds already coated with the coating composition in contact with the normally exposed seed surface with the particulate material adhered to the resulting coating of sugar and polymeric material is again coated with a coating composition of the same constituency followed by dispersing a particulate material over the resulting second coating of sugar and polymeric material while the coating is still tacky, and effecting at least an effective curing of said second coating of sugar and polymeric material. 
     
     
       29. The process of claims 19, 21, 22, 24 or 28 in which the polymeric material is a vinyl acetate homopolymer. 
     
     
       30. The process of claims 19, 21, 22, 24 or 28 in which the seed is rice or a leguminous plant seed. 
     
     
       31. The process of claims 15, 19, 21 or 28 in which a finishing coating composition comprising a water insoluble polymeric material in an inert organic solvent is distributed as a finishing coating over the exposed particulate coating in an amount sufficient to partially seal the coated seed without substantially increasing its germination time, and effecting a curing of said finishing coating composition. 
     
     
       32. The process of claim 31 in which the finishing coating composition comprises an isocyanate prepolymer as the polymeric material, ketamine as a co-polymerization agent and acetone as the solvent, and in which the polymeric material in the sugar containing coating composition is a vinyl acetate homopolymer.